Leak-nullifying means for telegraph systems.



I. H BELL.

LEAK NULLIFYING MEANS FOR TELEGRAPH SYSTEMS.

APPLICATION FILED MAR. 4. I9l5 Patented May 23, 1916.

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UNITED STATES PATENT oE JOHN HUME BELL, or EAST ORANGE. NEW JERSEY. ASSIGNOR, BY MEsNE ASSIGN MENTS, TO WESTERN ELECTRIC COMPANY. INCOIRPORATEDv A CORPORATION OF NEW YORK LEAK-NULLIFYING MEANS FOR TELEGRAPH SYSTEMS.

Specification of Letters Patent.

Application filed March 4, 1915. Serial No. 11,937.

To all whom it 1n ay concern Be it known that I, Jons' H. BELL, a subject of the King of Great Britain, residing at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Leak-Nullifying Means for Telegraph Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telegraph systems and more particularly to leak-nulli fying means for telegraph systems.

The object of this invention is to provide a new and improved means for nu lifying or rendering ineffective, with respect to the intermediate stations upon the line, the current leaks due to high resistance grounds upon the line between the terminal stations.

In accordance with the features of this invention, there is provided at each end of the line a double-wound relay normally energized over a local circuit to maintain the line closed, but which relay is adapted, upon the operation of the telegraph relay at its associated station. to open the line. The double wound relay has connected with one winding a condenser, the discharge of which causes the denergi zation of said double-wound relay to open the line circuit and thus remove the effects, of ground at the intermediate stations.

The drawing is a circuit diagram of a system wired in accordance with this in vcntion.

1n the drawing A and D designate terminal stations, and B and C intermediate stations connected with a line 5. Located at each of the terminal stations A and D.

10 and 11, the winding 10 being normally' energized from a local battery 12 through a resistance 13 to ground. The winding 11 of t he relay 9 is included in a circuit with a condenser 14 and a resistance 15 adapted to be closed through the front contact 16 of the relay 7. An armature 17 of relay 9 is adapted when said relay is energized, to close a contact 18 to maintain the Batteries 19 and 20 of opposite polarity, located at the terminal stations, are normally closed to line through the keys 6.

Referring now to the operation of the system, it will he noted that the armature 17 of the local relay 9 is normally .held attracted due to current through the winding 10 from the battery 12. Assume that the line is subject to heavy leakage but that station A can communicate with station D. \Vhen A opens his key in order to call station C, a current will still be flowing from the battery 20 at D, through the relays at B and C due to the line leakage.

The ad 7 ustment of relay 7 at station D however,

is such as to enable it to respond to the actuation of the key 6 at station A, but the relays at B and C being normally given less skilled attention than at the terminal station D may be out of adjustment with respect to the signals from station A, and consequently not to be actuated. Their armatures may, therefore, be held up due to the current, from battery 20 at station D feeding the leakage between Band A, and

may not respond to the current impulses sent out from station A. When the opening of the circuit at station A causes the line relay armature at station D to fall back, the condenser 14 discharges through the winding 11 of the local relay. This discharge. impulse produces a magnetic flux opposing and preponderating over that setup by the steady current through Winding 10. so that momentarily the armature of the local relay falls back, thus opening the line circuit at station D. \Vhen this occurs. the armatures of the relays at the intermediate stations which may have been held up due to inc. leakage. will drop back and thus be in osition to respond to signals from the terminal or intermediate stations. The great advantage of this scheme is that it requires, in addition to the usual apparatus at. each of the terminal stations. only one relay. the condenser and two resistances, and can be readily added to already existing equipments with but slight changes in the wiring.

\Vhat is claimed is:

1. In a telegraph system a line circuit, terminal stations and intermediate stations connected therewith. a source of current at each terminal station normally connected with the line, a relay at each terminal station, a contact closed by said relay when energized ,for maintaining the continuityof said line circuit, a continuously closed energizin circuit for said relay, and a de- "energizingcircuit for said relay rendered momentarily effective by the o ning and closing of'asending key where y the contmuity of said line. circuit will be momentarily, interrupted.

. 2. In a telegraph system a line circuit,

terminal stations and intermediate stations [connected therewith, a source of current t each terminal station normally connectedwith the line, a double-wound relay at each terminal station, a contactclos'ed by said relay whiz;

3. In a telegraph systema line circuit, terminal stations and intermediate stations connected therewith, a source of current at each terminal station normall connected with the line, a double wound re ay at each terminal station, a contact closed by said relay when energized to maintain the continuity of the line circuit, a continuously closed energizing circuit through one winding of said relay, a condenser in series with the other winding of said relay, and means for charging and discharging said condenser through saidsecond named winding upon the opening and closing of a telegraph key whereby said relay will be momentarily deenergized to open t e line circuit.

In Witness whereof, I hereunto subscribe my name this sixteenth day of Februarv A. D. 1915.

JOHN HUME BELL.

Witnesses: i

E. W. Animals, 0. J. Wonrn. 

